SUPER-STAKE
Frequently Asked Questions — Microbest Hard Chrome Bolt Carrier Group
Every gas key is staked. Very few are staked well.
// The Short Answer
The gas key is two screws holding the part that runs your rifle.
All the gas that cycles an AR travels down the gas tube and into the gas key on top of the bolt carrier. That key is attached with two screws. If those screws back out even slightly, gas leaks at the joint, the rifle short-strokes, and you get failures that look like a hundred other problems while you chase them. Staking — deforming carrier metal into the screw heads so they physically cannot rotate — is the fix, and it has been standard practice since the beginning. The problem is that staking is a hand operation with no universal standard, and an enormous amount of it is cosmetic: a light punch mark next to a screw head that never actually moved metal into anything. The Microbest Super-Stake group treats that operation as the headline feature rather than the last step on the line, and then puts the whole carrier in hard chrome.
// What Makes It A Super-Stake
Staking isn’t a dimple. It’s displaced metal.
A proper stake moves carrier material hard into the screw head so the screw is mechanically trapped. A cosmetic stake leaves a mark beside the screw and traps nothing. Both look similar in a photograph and behave completely differently at four thousand rounds. The difference is how much force went into it, whether the tooling was right, and whether anyone checked the result afterward.
This group addresses all three, and it does so by changing one operation rather than redesigning a carrier. Underneath, it is Microbest’s Premium Chrome BCG. On top of that it uses OCKS hardware from Michiguns — Optimized Carrier Key Screws, made specifically to be staked properly rather than generic fasteners. The staking is done by hand, heavy-duty, by Phillip Kimm of Bexar Arms; a named person doing a named operation, which is a different thing from a machine pass at the end of a production run. And the result is inspected: the staking opening is verified and the alignment is checked as its own step, because an operation nobody inspects is an operation nobody can stand behind.
The rest of the group is built to match. An 8620 carrier in the M16 full-auto profile for correct mass and hammer engagement. A C158 bolt, shot peened, high-pressure tested and magnetic particle inspected. A 4140 extractor with a black insert, and Sprinco five-coil chrome silicon springs on both the extractor and the ejector. Then the whole thing is hard chromed.
| The group | Specification |
|---|---|
| Base group | Microbest Premium Chrome BCG — same carrier, bolt, extractor and springs |
| Gas key hardware | OCKS — Optimized Carrier Key Screws, supplied by Michiguns; made to be staked, not generic fasteners |
| Staking | Hand-staked heavy-duty by Phillip Kimm, Bexar Arms |
| Staking inspection | Opening verified · alignment checked as a separate operation |
| Gas key | 4130 steel, phosphate |
| Carrier | 8620 steel, M16 full-auto profile |
| Finish | All hard chrome, except the gas key and extractor |
| Bolt | C158 — shot peened, high-pressure tested, magnetic particle inspected |
| Extractor | 4140 phosphate with black insert |
| Springs | Sprinco 5-coil chrome silicon — extractor and ejector |
| Weight | 11.6 oz |
// Questions We Get Asked
What exactly is “Super-Stake,” and what is it based on?
It isn’t a different bolt carrier group. It is Microbest’s Premium Chrome BCG with one operation replaced — and the whole product exists because that operation was judged worth doing differently:
- The base is unchanged. Same 8620 full-auto carrier, same C158 bolt shot peened and HPT/MPI tested, same 4140 phosphate extractor with black insert, same Sprinco springs, same 11.6 oz. Nothing about the group was redesigned.
- The factory staking was replaced by hand work. Instead of the production staking most BCGs receive, these gas keys are individually staked heavy-duty by Phillip Kimm of Bexar Arms in San Antonio — a named person performing a named operation, one carrier at a time.
- It’s built on the OCKS system. OCKS stands for Optimized Carrier Key Screws, supplied by Michiguns — fasteners made specifically to be staked properly rather than generic screws that happen to be in the hole. The heavy stake and the right screw are one idea, not two.
- And it’s inspected afterward. Mil-spec key opening verified, optimum alignment checked, on each unit. That last step is what turns a hand operation into a standard.
If every carrier is staked, why is this worth paying extra for?
Because “staked” describes an intention, not a standard. Three things separate a stake that holds from one that doesn’t:
- Force. Displacing steel into a screw head takes real pressure. A light punch mark satisfies a visual inspection and traps nothing, and you find out which one you have when the rifle starts short-stroking.
- Hardware. The screws themselves matter. OCKS hardware is made for this job, rather than being a generic fastener that happens to be in the hole when someone reaches for a punch.
- Verification. This group’s staking opening is verified and its alignment checked as a separate operation. Nobody inspects a cosmetic stake, because there is nothing to measure.
What actually happens if a gas key loosens?
Gas escapes at the joint instead of driving the carrier. The rifle short-strokes — failures to extract, failures to lock back, sluggish cycling — and the symptoms look identical to a gas port problem, a buffer problem, or bad ammunition. People replace three other parts before they check the two screws. That diagnostic cost is part of what the staking buys you.
Why is the gas key phosphate when everything else is chrome?
Because staking works by displacing metal, and a hard plated surface resists being displaced and can chip rather than flow. Leaving the key and the extractor in phosphate keeps those parts behaving the way the operations performed on them need them to behave. It’s a deliberate choice, not an oversight in the finishing.
What does hard chrome do for me?
Three things: a hard surface that resists wear, a slick one that reduces friction against the receiver and inside the carrier, and a corrosion-resistant one. This isn’t exotic — Mil-Spec already calls for chrome inside the carrier bore and the gas key. This group extends a proven practice across the whole part.
Is it easier to clean?
Noticeably. Carbon doesn’t key into a hard smooth plated surface the way it does into porous phosphate, so most fouling wipes off rather than needing to be scraped. If you’ve only ever cleaned a phosphate carrier, the difference is the first thing you’ll notice about owning this group.
Why does a bright finish matter?
It’s an inspection advantage that rarely gets mentioned. Cracks, unusual wear patterns, and gas leakage tracks are far easier to see on a bright surface than on a black one. If you or your armorer are actually looking at the bolt group on a schedule, chrome shows you what’s happening to it.
What do the Sprinco springs contribute?
Chrome silicon resists taking a set under heat and cycling better than standard spring wire, which matters most for the extractor. A weak extractor spring is one of the most common causes of extraction failures on a high-round-count rifle, and it’s a part most owners never think about until it costs them a stage or a string.
Why a full-auto profile carrier on a semi-auto rifle?
Mass and timing. The M16 profile carries more weight and shields the firing pin more fully than a lightweight semi-auto carrier, which gives a smoother, more consistent cycle and correct hammer engagement. It has nothing to do with rate of fire and everything to do with the carrier doing its job the same way every time.
How does this compare to your polished DLC group?
Both are excellent and we fit both. They’re built around different priorities:
- Polished DLC — the lowest friction and the best fouling release available, chosen for precision rifles where cycling consistency across a long string is the requirement. Thinnest coating, most expensive.
- Super-Stake hard chrome — the gas key joint treated as the priority, with a proven plating and a bright surface that inspects easily. Chosen where reliability under round count and serviceability matter most.
- Either can carry the HMB bolt. We offer this group with the HM Defense HMB bolt in hard chrome, so the staking and the bolt’s reinforced cam pin location come together in one group.
Will it make my rifle more accurate?
No. This is a reliability and service-life group, and we’re not going to dress it up as anything else. Your barrel and your ammunition set your group size. What this buys is a rifle that keeps running the way it ran when you bought it.
Do I need to check the staking myself?
Look at it during normal cleaning, the same as you’d look at the bolt lugs and the extractor. You’re checking that the displaced metal is still hard against the screw heads and that there’s no carbon tracking around the base of the key, which is what gas escaping looks like. If either looks wrong, stop shooting it and send it in.
Who’s it for?
Anyone putting serious round count through a rifle, and anyone whose rifle has a job. Agencies, competitors, high-volume training, and suppressed rifles that run hot and dirty. If you shoot a few hundred rounds a year, a good standard carrier group will serve you honestly — and we’ll tell you that rather than upsell you.
// What The Super-Stake Group Does Not Do
A better carrier group is not a different rifle.
- It doesn’t change your point of impact. See Q 10. Carrier groups govern reliability and cycling, not group size.
- It doesn’t fix a gas system that’s wrong. An overgassed or undergassed rifle stays that way with any carrier in it. Port, buffer, and spring are the answer to that problem.
- It doesn’t make the staking maintenance-free. Well-staked screws are extremely unlikely to move, but you still look at them. A part designed not to fail still gets inspected.
- Chrome is a plating, not armor. It resists wear and corrosion; it does not make the carrier stronger. Strength lives in the 8620 carrier and the C158 bolt underneath it.
- It doesn’t replace headspace gauging. Any bolt is gauged against the specific barrel extension it will run on, every time, regardless of what group it came in.
// What You Get
The carrier group is identified on your build record by make, model, finish, and bolt configuration — along with the headspace gauging result for that bolt against your barrel. Inspect the staking and the base of the gas key on your normal cleaning schedule and you will almost certainly never think about either again. If you ever see carbon tracking around the key or a screw head that looks like it has moved, send the rifle in rather than chasing symptoms.
Two screws. Staked like they matter.